CS3 Listening theinterrupt.com

Call sign CS3

The
Interrupt

People hear a break. A processor hears a request. An interrupt is the moment a system agrees to stop what it is doing, because something else has become true.

A processor spends its life in a loop. Fetch, decode, execute. Then again. The loop is fast, and it is deaf. The world gets in by raising a single line: a numbered request to be heard. The machine saves its place. It runs the thing that cannot wait. Then it returns, on purpose.

A quiet line, one interrupt, then the line again The trace runs flat, rises into a single spike, settles, and continues. The spike is the request that could not wait. IRQ
Saved place Handler Return
  1. 01

    Signal

    Something the current instruction cannot see. A key, a packet, a clock, a person at the door.

  2. 02

    Priority

    The line stays quiet so the real request can land. Rank is the whole discipline. Volume is not.

  3. 03

    Return

    A true interrupt gives the machine back. The place is restored. The loop goes on, changed by the fact that it stopped.

On the original PC, interrupt line three belonged to the serial port. A wire left open for a machine that was somewhere else.

CS3 is that wire. This station is for work that should be allowed to break the schedule: notes, tools, and short transmissions from outside the loop.

The loop can wait. The line stays clear.